Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard device, a trackball device, or the like. Via the keyboard device, characters and symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of the input devices pay much attention to the development of keyboard devices. That is, the manufacturers of the input devices make efforts in designing novel keyboard devices with diversified functions. For operating the keyboard device in a dark environment, one of the conventional approaches is to install an electroluminance plate within the keyboard device and use the electroluminance plate as a light source. When the electroluminance plate is powered by electricity, the electroluminance plate is enabled to emit a light beam, and thus the keyboard device exhibits luminous efficacy. However, since the electroluminescence plate is only able to emit a monochromatic light beam, the conventional luminous keyboard device can only exhibit a single light color. In another conventional approach of operating the keyboard device in a dark environment, light emitting diodes (LED) are installed under respective keys to be used as dot light sources. However, the approach of installing the light emitting diodes under respective keys may increase the fabricating cost of the luminous keyboard device and reduce the heat-dissipating efficiency of the luminous keyboard device.
For solving the above two drawbacks, a luminous keyboard device is disclosed in for example Taiwanese Patent Publication No. TW200945113. FIG. 1 is a schematic top view illustrating the outer appearance of a conventional luminous keyboard device. As shown in FIG. 1, the conventional luminous keyboard device 10 comprises plural keys such as numeric keys, symbol keys, alphabetic keys, arrow keys, space key, and function keys. Moreover, each of the alphabetic keys “W”, “A”, “S”, “D”, the space key, the “Enter” key and the up/down/left/right arrow keys is illuminated in a color different from other keys. For example, the conventional luminous keyboard device 10 is a keyboard device for a notebook computer.
FIG. 2 is a schematic cross-sectional view illustrating the conventional luminous keyboard device of FIG. 1 and taken along the line A-A′. As shown in FIG. 2, the conventional luminous keyboard device 10 comprises a keypad module 100 and an illumination module 200. The illumination module 200 is located under the keypad module 100. The keypad module 100 comprises plural keys 112, 114, plural elastic elements 120, plural scissors-type connecting element 130 and a membrane switch circuit member 140. When one of the keys 112 and 114 is depressed by a user, a corresponding key signal is generated. In response to the key signal, a command is provided to a computer (not shown) that is in communication with the conventional luminous keyboard device 10, thereby controlling execution of a corresponding program. The illumination module 200 comprises a light-shading member 210, a light guide plate 220, a reflector 230, a first light-emitting element 240, and a second light-emitting element 250. The light guide plate 220 comprises a first light-guiding region 222, a second light-guiding region 224 and a light-shading region 226. The light-shading region 226 is arranged between the first light-guiding region 222 and the second light-guiding region 224. For example, the light-shading region 226 is a gap. Through the light-shading region 226, the light guide plate 220 is divided into the first light-guiding region 222 and the second light-guiding region 224. For enhancing the light-shading efficacy, the light-shading region 226 further contains a light-shading material (or a reflective material) 227. The light-shading material (or a reflective material) 227 is formed on at least one interface between the light-shading region 226 and the first light-guiding region 222 or the second light-guiding region 224.
In the illumination module 200, the first light-emitting element 240 is used for emitting a first color light beam (e.g. a white light beam) to the first light-guiding region 222. The second light-emitting element 250 is used for emitting a second color light beam (e.g. a blue light beam) to the second light-guiding region 224. The first light-guiding region 222 and the second light-guiding region 224 are separated from each other by the light-shading region 226, so that the first color light beam and the second color light beam are not mixed with each other.
The light-shading member 210 has a predetermined pattern. The first color light beam from the first light-emitting element 240 and the second color light beam from the second light-guiding region 224 are transmissible through the predetermined pattern, so that the possibility of scattering the light beams will be reduced. Moreover, the light-shading member 210 may be a light-shading pigment layer or a thin resin film with a light-shading pigment coating. For example, the thin resin film is a polyethylene terephthalate (PET) thin film or a polyvinylchloride (PVC) thin film. The light-shading member 210 has plural openings 215 corresponding to the positions of the keys to be illuminated. Consequently, the light beams can be guided by the light guide plate 220 to be directed to the corresponding keys (e.g. the keys 112 and 114). Moreover, for preventing the light beams from being scattered through the region between every two adjacent keys, the openings 215 of the light-shading member 210 are slightly smaller than the corresponding keys (see FIG. 2).
The light guide plate 220 is located under the light-shading member 210 for guiding the first color light beam and the second color light beam, so that the light guide plate 220 is served as a light transfer medium. The first light-guiding region 222, the second light-guiding region 224 and the light-shading region 226 of the light guide plate 220 are integrally formed with each other. Moreover, the second light-guiding region 224 is surrounded by the light-shading region 226 (i.e. the gap), so that the first light-guiding region 222, the second light-guiding region 224 and the light-shading region 226 are respectively defined (see FIG. 3).
FIG. 3 is a schematic top view illustrating the illumination module of the conventional luminous keyboard device of FIG. 2. As shown in FIGS. 2 and 3, plural first light-emitting elements 240 are located beside at least one lateral edge of the first light guide region 222. The first color light beam from the first light-emitting element 240 is guided by the first light-guiding region 222 and transmitted through the openings 215 of the light-shading member 210. Consequently, at least a specified key (e.g. the key 112) of the keypad module 100 is illuminated by the first color light beam. On the other hand, at least one second light-emitting element 250 is disposed within each second light-guiding region 224. The second color light beam from the second light-emitting element 250 is guided by the second light-guiding region 224 and transmitted through the openings 215 that are located over the second light-guiding region 224. Consequently, at least a specified key (e.g. the key 114) of the keypad module 100 corresponding to second light-guiding region 224 is illuminated by the second color light beam. It is noted that the positions, sizes, number and distribution of the second light-guiding region 224 may be determined according to the specific keys to be illuminated by the second color light beam. For example, the second light-guiding region 224 under the alphabetic keys “W”, “A”, “S” and “D” has inverted T-shaped profiles. In addition, the second light-guiding region 224 under the space key has a rectangular profile. The reflector 230 is located under the light guide plate 220. The first color light beam or the second color light beam scattered by the light guide plate 220 can be reflected by the reflector 230 in order to be reused. As a consequence, the light utilization efficiency is enhanced, and the scattered light is reduced.
The first light-emitting element 240 and the second light-emitting element 250 are light emitting diodes for emitting different color light beams, so that the predetermined positions of the keypad module 100 are illuminated in different colors. For example, the first light-emitting element 240 is a white light LED and the second light-emitting element 250 is a blue light LED. Consequently, the keypad module 100 will exhibit a white-color area (e.g. the position of key 112) and a blue-color area (e.g. the position of the key 114).
From the above discussions, the structures and operating principles of the conventional luminous keyboard device 10 for exhibiting various light colors have been described. The keys of the luminous keyboard device 10 may exhibit various colors for facilitating the user to recognize and operate the keys of the luminous keyboard device 10 in a dark environment. However, the processes of additionally installing the second light-emitting element 250, the second light-guiding region 224 and the light-shading region 226 in the light guide plate 220 are very complicated, very difficult and time-consuming. In other words, the fabricating cost of the luminous keyboard device 10 is increased.
Therefore, there is a need of providing a luminous keyboard device that is fabricated in a simplified process.